Assays for thyroid-stimulating hormone using dried blood spotted filter paper specimens to screen for hypothyroidism in older children and adults.

Abstract

Symptoms of hypothyroidism in adults can be mistaken for medical and psychiatric diseases, as well as for general signs of ageing such as weakness, lethargy and fatigue. The incidence of hypothyroidism is many-fold higher in adults than in newborn children. The latter have been routinely screened for the condition using filter paper dried blood spots (DBS) for nearly three decades but this cost-effective screening technique has only recently been applied to adults. This study was undertaken to show that DBS testing in adults and older children is an accurate way to screen for hypothyroidism. Serum and DBS specimens were collected from adults and children. Assays were run on both specimens and the results correlated. In addition 972 specimens were collected from adults at community centres and nursing homes. Follow-up studies were performed on patients with positive results. The correlation coefficient for 118 matched serum and DBS specimens was 0.99. Thyroid-stimulating hormone (TSH) values were elevated in 50 of the 972 adults from nursing homes and community centres. Thirteen of these individuals were on thyroid medication and 28 had either high serum TSH or high thyroglobulin (TgAb) or thyroid peroxidase (TPOAb) antibody levels. Individuals can be screened for hypothyroidism by collecting finger stick DBS specimens at community centres, nursing homes and other locations which can be mailed by regular postal service to a central laboratory for accurate and inexpensive testing.